1. Field of the Invention
This invention relates to the field of natural dietary supplements. It relates particularly to dietary supplements that are able to aid the prevention or inhibition of infection, promote immunological stimulation or increase tissue repair or healing. It is directed particularly towards the supplementation of human diets, and provides for enhanced absorption of the proteinaceous active ingredients in the oral cavity.
2. Background of the Invention
Nutrition is a critical determinant of immunological competence and of the individual's ability to resist infection and physiological stresses. The health of individuals is affected by poor decisions in society's management of new technology over the past five decades. In particular, the routine use of antibiotics, the consumption of processed foods and the pollution of the environment have resulted in multiple adverse influences upon health. Among these may be included the proliferation of new strains of bacteria and viruses that are resistant to existing antibiotic and antiviral agents, compromised immune systems resulting from chemical pollutants in food, water and air, as well as impaired ability to repair tissue and muscle. Additionally, emotional and physical stresses from employment, family, exercise and the natural effects of aging reduce the effectiveness of the immune system and tissue repair processes.
The continuing widespread use of antibiotics in medicine and agriculture reinforces the selective pressures that increase the types and extent of antibiotic-resistant microbes in the environment, which then substantially increases the cost of treating infection. Moreover, administration of antibiotics frequently causes disruption of the normal bacterial flora colonizing the individual's digestive tract, with results that are particularly undesirable in weakened patients.
The physiological rigors to which an individual's body is exposed in the modern environment, which include the chemical pollutants and antibiotic-resistant microbes discussed above, indicate the advisability of boosting the immune system to facilitate the body's abilities to resist and cope with infection, and to assist the natural, self-healing processes. Two groups of individuals are particularly susceptible to infection and the side effects of treatment: young children and the aged. These individuals may respond poorly to physiological or environmental challenges because they typically possess immune systems that are, in young children and in the aged respectively, immature or damaged. Consequently, natural stimulation of these individuals' immune systems is particularly desirable.
3. Description of the Prior Art
Stimulation of the immune system may occur if the appropriate proteins are absorbed into an individual's bloodstream. Yet these proteins are not only degraded rapidly by the acidic and enzymatic conditions of the stomach and intestine but they are also expensive to obtain, even in the quantities and formats used for experimental demonstrations: Lonnerdal & Iyer, 1995, Annu. Rev. Nutr., 15: 93-110. Thus attempts to formulate an effective dietary supplement able to generate and maintain a state of immune stimulation in an individual have been unsuccessful.
If the components of a dietary supplement were to possess, in addition to nutritional characteristics, abilities that aid the body's capacity to resist fresh infection, to suppress existing infection or to increase tissue repair and healing, such abilities would naturally prove advantageous for achieving the general health enhancing purposes outlined above. As indicated below, those skilled in the art of the respective fields recognize that each of the two proteinaceous products colostrum and lactoferrin is able to perform beneficial activities of this type: see, for example, Wang, et al., 1995, J. Leuk. Biol., 75: 865-874, and Burrin et al., 1995, Pediatr. Res., 37: 593-599.
Colostrum is the pre-milk produced immediately after birth before the breast secretions stabilize into milk. Prime colostrum from cows is obtained within the first six hours after calving and contains more than twice the milk solids and four times the protein found in milk from the same cow obtained forty-eight hours later. The concentrations of digestive enzymes, immunoglobulins, cytokines, interferons, glycoproteins, proline-rich peptides and vitamins A, D, E and K are all higher in prime colostrum than in the later breast secretions. The immunoglobulin fraction of the prime colostrum provides the newborn with antibodies, lactoferrin and immune enhancers. These components offer the newborn protection against viruses, bacteria, allergens and toxins, assisting desirable Acidophilus bacteria to start the colonization of the newborn's intestine and help prevent the development of gastrointestinal infection. Proline-rich peptides (e.g. colostrinin) are immunomodulatory peptide components of colostrum: Janusz and Lisowski, 1993, Arch. Immunol. Therap. Experiment., 41: 275-279. These proline-rich peptides are regulators of the thymus gland, which in turn produces T-lymphocytes that neutralize antigens, including infectious agents such as bacteria and viruses. Colostrum also contains a combination of growth factors that combat disease, reduce infection and enable the newborn to grow healthily and to heal rapidly: see, for example, Oda et al., 1989, Comp. Biochem. Physiol., 94A: 805-808 and Xu et al., 1994, Biol. Neonate, 66: 280-287. That even healthy adults may benefit from the administration of colostrum is suggested by studies showing that bovine colostrum whey increases serum levels of insulin-like growth factor (IGF-I) in athletes undergoing training: Mero et al., 1997, J. Appl. Physiol., 1997, 83: 1144-1151. Colostrum balances blood sugars during periods of hyperglycemia or hypoglycemia, slows catabolism and the breakdown of muscle protein, and it stimulates fat utilization.
In sum, prime colostrum contains powerful healing, growth and repair factors that activate numerous immune, healing, growth and repair systems and assist in synthesis, retention and repair of muscle, bone, nerve and cartilage. As the body ages, becomes weakened by illness, or is subjected to physical stresses, it produces less and less of the growth, healing and repair factors that are needed to overcome illness and to heal quickly.
Ettinger, U.S. Pat. No. 4,762,822 (expired) describes the use of human colostrum as a source for extracting ganglioside, with human milk or mammalian brain being alternative sources. As one of several alternative components of young mammals' dietary supplements the extracted ganglioside is used to improve mother's milk substitute foods or for reducing the numbers of gastrointestinal disease-producing organisms in a young mammal.
Lactoferrin is a protein that is secreted in milk, tears, mucus and saliva, and is expressed by white cells at the site of attack by numerous pathogens. A primary function of lactoferrin is to bind iron at the molecular level and thereby act as a highly effective antimicrobial agent. Iron is an essential growth factor for virtually every cell and microorganism, and free iron promotes the growth of pathogens in the intestines (bacteria, viruses and fungi), permitting invasion of the rest of the body through the intestinal walls: Gillon Ward et al., 1996, J. Trauma, Inj. Inf. Critical Care, 41: 356-364. Lactoferrin is released by cells to absorb free iron that would otherwise be available to bacteria, viruses and fungi for growth. Unlike synthetic antibiotics, to which bacteria may develop resistance through mutation, lactoferrin exerts its bacteriostatic effect as long as the bacteria require iron for growth.
Additionally, lactoferrin is recognized by specific receptors in mammalian tissues to release iron to the body for normal, healthy cell growth. Unlike synthetic antibiotics, lactoferrin has the ability to bind iron, transport it and then release the iron specifically to the body's own cells through cell surface lactoferrin receptors.
Lactoferrin is a multifunctional protein that is expressed in a variety of cell types under different mechanisms of control. It has been demonstrated that lactoferrin plays a central role in the inflammatory defense processes. Released in abundant quantities by neutrophils attracted to the site of an invasion, lactoferrin binds the iron made available by serum and damaged erythrocytes. Monocytes and macrophages ingest the iron-saturated lactoferrin, which has also been implicated in the production of metastable oxygen metabolites associated with bacterial destruction within these blood cells: Wang, et al., 1995, J. Leuk. Biol., 75: 865-874. Lactoferrin also regulates the release of tumor necrosis factor alpha (TNF-.alpha.) and interleukin 6 (IL-6) in vivo: Machniki et al, 1993, Int. J. Exp. Path. 74: 433-439.
Due to the iron absorption and release functions of this protein, lactoferrin is the body's primary regulator of iron, a major bio-regulator of the digestive tract and a natural bacteriostatic agent having indirect but broad antibiotic effects. Yet the cost and availability of human lactoferrin, purified from human breast milk, restricts its use to research.
Lactoferrin's iron-binding bacteriostatic effect, coupled with its general abundance in breast milk, has led to numerous studies in new-born mammalian offspring, prompting its incorporation into Japanese baby formula since approximately 1993. Lactoferrin B is an amino terminal peptide of bovine lactoferrin generated by pepsin digestion and has been shown to have a potent bacteriocidal activity against a diverse range of potentially pathogenic bacteria: Bellamy et al, 1992, J. Applied Bacteriol., 73: 472-479. The importance of lactoferrin in newborn humans for ensuring the appropriate formation and development of the gastrointestinal tract, its bacterial colonization and to enable nutrients to be absorbed effectively, has also been demonstrated.
Many of these functions of lactoferrin are reviewed by Lonnerdal & Iyer, 1995, Annu. Rev. Nutr., 15: 93-110. Yet these authors note that the relative efficacy of using either lactoferrin from other species, or recombinant human lactoferrin for treatment of humans is unproven. This is because adequate quantities of human lactoferrin have not been isolated to supply clinical studies, and recombinant human lactoferrin will not accurately reproduce the protein's glycan composition.
Tanaka et al., U.S. Pat. Nos. 5,098,722 and 5,008,120 disclose methods of preparing iron-fortified beverages that contain a solution of purified bovine lactoferrin and provide high bio-availability of iron.
Tomita et al., U.S. Pat. No. 5,304,633 disclose fragments of milk lactoferrin having potent antimicrobial activity. Kunio et al., U.S. Pat. No. 5,576,299 disclose the use of lactoferrin for preventing and treating the opportunistic infections that arise in immuno-compromised individuals. Yamamoto et al., U.S. Pat. No. 5,725,864 disclose the use of an iron-binding protein, of which lactoferrin is one of several examples, for inhibiting infection or suppressing growth of human immunodeficiency virus: the protein is administered by diffusion through any of several epithelial membranes, or by injection. Valenti & Antonini, U.S. Pat. No. 5,834,424 disclose the use of compositions containing lactoferrin or other iron-binding proteins for treating Gram-positive bacterial infections.
Nichols & McKee, U.S. Pat. No. 4,977,137 describe the use of milk lactoferrin from human and other mammalian sources as a dietary ingredient or supplement. The lactoferrin promoted growth of the gastrointestinal tract of human infants or non-human animals immediately on birth. Konig et al., U.S. Pat. No. 5,466,669 disclose an immunostimulatory agent comprising a peptide derived from lactoferrin.
Headon et al., 1990, PCT/US90/02356, European Pat. No. 0 471 011 B1, disclose the verified cDNA sequence of human lactoferrin. Kruzel, 1991, PCT/US91/01335 discloses human lactoferrin expressed from recombinant DNA, its method of production and purification and its use for supplementing the diet with trace elements or as a topical antiseptic. Kruzel et al., 1995, PCT/US95/05653 disclose the cloning, expression and uses of recombinant human lactoferrin for retarding food spoilage, as a topical antiseptic, for inhibiting microbial growth in or on a mammal, for regulating iron levels within a mammal or for a nutritional supplement.
Citrus pectin obtained from citrus peel is modified by a standard technique involving limited proteolysis, facilitating passage into the bloodstream of the smaller polypeptide products. Galactose residues located on the surface of both the original pectin glycoprotein and the more soluble polypeptide products bind lectins, including cell surface proteins of some cancer cells: Raloff, 1995, Science News, 14: 134. Modified citrus pectin consumed in drinking water has been shown to halt the spread of prostate cancer cells: Pienta et al., 1995, J. Nat'l. Cancer Inst., 87: 348-353.
See, U.S. Pat. No. 5,747,464 discloses the use of apple pectin bound irreversibly to .beta.-sitosterol in a composition which is used as a dietary supplement for inhibiting absorption of fat and cholesterol from the gut.
The strongly acidic conditions of the stomach, and the function of the proteolytic enzymes and zymogens produced in the pancreas and acting in the intestines, are well known to inactivate and degrade the delicate structures of proteins, such as the components of the dietary supplements described here. As reviewed by Lonnerdal & Iyer, 1995, Annu. Rev. Nutr., 15: 93-110, the species-specific glycosylation of lactoferrins from different mammalian sources may provide protection from proteolysis for lactoferrin ingested naturally from maternal milk, and cross-species administration of lactoferrin would be expected to be far less effective. Even if the lactoferrin succeeds in reaching the small intestine intact, specific lactoferrin receptors enable human lactoferrin to deliver iron to the mucosal cells of human small intestine, whereas bovine lactoferrin is incapable of doing so: Cox et al., 1979, Biochim. Biophys. Acta, 558: 129-141.
In spite of the knowledge of the beneficial properties of either colostrum or lactoferrin when used individually, there remains a continuing need for an economical dietary supplement to boost the body's own defense and repair systems and to provide for increased energy, stamina, resilience and tissue repair. The components of the supplement must be obtainable from economic and abundant sources, yet remain effective for administration to humans, and preferably to a broad range of recipient mammals. Moreover, such a dietary supplement must be absorbed effectively, without the degradation of protein constituents that is associated with regular digestive processes such as the destruction of delicate immunoglobulins by acids in the stomach.
The oral cavity contains a plethora of mechanisms to counter the survival of infectious agents that enter through the mouth and nose: secreted with the saliva are broad-spectrum IgA antibodies, lysozyme and small quantities of lactoferrin, and lymphoid cells enter the oral cavity through the gingiva. In addition, it has recently been recognized that external factors may also deliver signals that modulate immune responses: these factors include cytokines such as the interferons, as well as hormones, growth factors and cellular antigens.
Studies aimed at preventing allergic inflammation in rodents have indicated that administration of interferon to mice by oral feeding could be as effective as intraperitoneal injection. Thus oral administration of either antigens or cytokines may be capable of modulating a variety of physiological reactions, including immune responses. Possible routes of mediation are: (a) taste buds of the tongue, connected by nerves to hypothalamus collateral centres, control appetite and energy utilization; (b) a spectrum of mucosal and secretory cell types present in the oral cavity that are capable of responding to cytokine or antigen signals and releasing further cytokine messages; (c) epithelial cells of the oral cavity, which are likely to be the natural recipients of signals entering the mammalian mouth: in the adult these would be primarily signals from antigens, whereas for the neonatal mammal important signals would also be received from ingested maternal cytokines and maternal hormones; (d) the submucosal tissue of the oral cavity, which secretes immunoglobulin IgA. Small amounts of either cytokine or antigen may be recognized as antigen by a responsive cell, resulting in immune activation via initiation of the cytokine cascade, whereas large doses or extended administration may induce tolerance: studies have shown that interferon administered in large doses to humans may be less effective than minimal quantities. Thus the response will frequently be individual or case dependent and may be strongly influenced by additional physiological or environmental factors.
The implications of these immunological studies have been reviewed recently (Georgiades, 1998, Biotherapy, 11: 39-51) with the conclusion that the tolerance phenomenon is not only limited to the oral administration of antigen but may occur when immunization is attempted via any mucosal membrane, such as the nasal tract. In the light of such conflicting results and controversial hypotheses it could be considered counter-intuitive, and certainly unpredictable, to attempt to stimulate or potentiate an immune response by administering cytokinins and immunoglobins orally by means of a combination of prime colostrum and lactoferrin.
4. Objects of the Invention
The invention addresses the requirement for an effective and economical dietary supplement comprising one or more natural stimulators of immune function, prevention of and protection from infection, and improved tissue repair and healing. Furthermore, this supplement must be provided in a convenient format that permits absorption of the active components into an individual's bloodstream in a manner that avoids the body's normal digestive mechanisms. The present invention emphasizes the efficacy of oral administration of the dietary supplement and promotion of the supplement's efficient absorption through the oral cavity's epithelial lining by presenting the supplement in a `mucosal delivery format` (MDF). Those MDFs of the invention that are preferred, e.g. chewable lozenges, also render the dietary supplement of the invention particularly adaptable to self-monitored dosages, and are especially appropriate for regimes of self administration.